Transport evidence of triply degenerate nodal semimetal YRh6Ge4

TL;DR

This study investigates the magnetotransport properties of YRh6Ge4, revealing signatures of chiral anomaly and nearly massless fermions, supporting its classification as a triply degenerate nodal semimetal and providing insights into three-component fermions.

Contribution

The paper provides experimental evidence of chiral anomaly and quantum oscillations in YRh6Ge4, confirming its status as a triply degenerate nodal semimetal and closer to the Fermi level than similar materials.

Findings

Large negative longitudinal magnetoresistance observed

Quantum oscillations reveal nearly massless fermions

Fermi pockets are smaller and closer to Fermi level than in similar materials

Abstract

We have investigated magnetotransport properties of YRh6Ge4, which was recently predicted to be a triply degenerate nodal semimetal. We find it exhibits remarkable signatures of a chiral anomaly, manifested by large negative longitudinal magnetoresistance, quadratic field dependence of magnetoconductance and planar Hall effect. Furthermore, we have also observed Shubnikov-de Haas (SdH) quantum oscillations in the magnetoresistivity measurements on this material. The analyses of the SdH data reveal two point-like Fermi surfaces and these pockets are found to host nearly massless fermions. The small size of these Fermi pockets is in a good agreement with the theoretical prediction that the triply degenerate point in YRh6Ge4 is much closer to the Fermi level than previously demonstrated triply degenerate nodal semimetals such as MoP and WC. These results suggest YRh6Ge4 may serve as a model system to probe exotic properties of three-component fermions and understand their underlying physics.